(a) Field of the Invention
The present invention relates to a motor driving device for vehicles, and more particularly to a technology of a brushless DC (BLDC) motor driving device configured to optimize electromagnetic compatibility (EMC).
(b) Description of the Related Art
In general, a BLDC motor does not include a brush serving as a commutator of a general DC motor, and is designed to retain unique characteristics of the DC motor without change. The BLDC motor includes a rotor, a stator composed of a 3-phase coil (U-phase coil, V-phase coil, and W-phase coil), a rotor composed of a permanent magnet, and a position detection sensor.
The BLDC motor applies a current to each phase of the stator coil of the 3-phase BLDC motor, and generates a magnetic field in the coil due to the flowing current so that the rotor begins to rotate. In this case, the BLDC motor detects the magnitude of a magnetic field of the rotor, and sequentially switches on or off the switching elements for switching the direction of a current flowing to each phase of the coil in response to the intensity of detected magnetic field, such that the rotor can continuously rotate in one direction.
Meanwhile, electromagnetic compatibility (EMC) indicates that an objective device is affected by electromagnetic waves generated from other devices. If the objective device is affected by EMC, a failure rate of a motor or controller of the device inevitably increases.
In accordance with a conventional motor driving semiconductor, resistors and capacitors located outside of the semiconductor are replaced with others, and a switching time of the switching element contained in a motor controller is adjusted to perform EMC tuning. In particular, passive elements (e.g., resistors, capacitors, etc.) contained in the motor controller are replaced with other elements during the development process, and tuning of electromagnetic waves is performed.
However, the conventional motor driving device has difficulty in discriminating between a rising time and a falling time of motor control pulses, so that it is very difficult for the conventional motor driving device to be precisely tuned. In addition, the conventional motor driving device is affected by variation of an external power source such that it has technical limitation in EMC tuning.